1. Field of the Invention
This invention relates generally to prison cell door operating and locking mechanisms and, more particularly, to remote controlled operating and locking mechanisms for sliding prison cell doors.
2. Prior Art
In prisons, it is desirable for prison cell doors to be remotely operable and lockable. Electrical operation of each individual cell door is preferable, enabling complete electrical control of each cell from a remote location. It is also preferable that individual electrical operation of each door be accomplished via an electric motor over each door. It is also desirable that the officer operating the cell door remain at the remote location throughout the operation cycle of the door, usually from a locked closed position to a locked open position and vice versa. This is especially true in situations where electrically operated door mechanisms fail, such as in power failure situations. Prior art cell door systems comprising over the door motors have provided for remote manual operation of doors, but only for gang opening or closing situations. In other words, in manual mode, all doors in a particular cell block which is serviced by a particular remote control can be opened or closed, but only in unison. Other prior art systems are available which allow selective individual manual operation of a particular cell door, but only if an officer enters the cell block and activates a release for the cell to be opened or closed. In some states, fire regulations additionally require that there be a capability for releasing cell doors for inmate control (i.e. releasing control of the door to the inmate so he/she can manually open the door). When this situation presents itself, it is desirable that an officer at a remote location be able to retrieve or release control of the door without entering the cell block. If some doors are open while others are closed, an indexing mechanism is necessary to retrieve manual control of the doors. Prior art devices have not addressed the problem of quickly relinquishing or retrieving control of individual doors to or from the inmates.
Most sliding cell doors are provided with a mechanism for actuating a vertical lock bar which either locks or unlocks the door in an open or closed position with respect to a fixed frame or grating. In order to achieve the desired situation wherein opening and closing, as well as locking and unlocking is controlled by an operator at a remote location, the vertical lock bar is usually moved between a locked and an unlocked position by travel of the door mechanism a designated distance past the open or closed position of the door. This additional movement of the door mechanism is known as "overtravel". Various means have been utilized in the prior art to achieve overtravel. Most involve complicated and expensive mechanical or electrical arrangements which may become jammed either inadvertently or through intentional inmate action.
It is also desirable to achieve a degree of redundancy in such locking mechanisms, while preserving the advantages of remote operation. Redundancy is necessary in riot conditions, wherein inmates have been known to obtain tools and attack the cell doors and lock bars. No device is currently available which offers selective remote operation of cell doors with a motor over each door in either electrical or manual mode, while achieving simplified overtravel and redundancy.